How to NOT duplicate data when copy-pasting?
The "object" doesn't store the actual data, like the mesh. That's stored in a datablock.

Each object normally has its own datablock, but you can assign any datablock to any object (of the same type), effectively creating linked clones. When you edit one object, you're actually editing the datablock, so any other objects with the same datablock will change in tandem.

Anything on the Object tab (the orange cube in the screenshot below) is part of the object, not the datablock. These settings will not be shared between objects.




The datablock selector